1. Field of the Invention
This invention relates to the field of test equipment and methods for loading the output voltage of a power supply. This invention is particularly related to burn-in test equipment that is used to load the output of a power supply having a sinusoidal output voltage and output frequency that is substantially equivalent in amplitude and output frequency to the voltage and frequency of the electrical service providing electrical power to the power supply. This invention is more particularly related to the field of test equipment used to load un-interruptable power supplies (UPS) that provide temporary sinusoidal voltage service at relatively high output power levels such as the UPS power supplies that provide back-up power for computer facilities.
2. Description of Prior Art
After an ac power supply is manufactured, it is typically operated in a burn-in test circuit at or near its rated capacity for a period of time calculated to provide an increased level of confidence in the reliability of the unit to be delivered.
Resistors are conventionally used to load the output of an ac power supply such as a UPS power supply during burn-in test. The power dissipated by the resistive load is typically dissipated by convection or conductive cooling. The energy that is dissipated is typically wasted along with the losses in the power supply attributable to the conversion and control process necessary to provide the required output power. The energy that is dissipated in the test must be purchased by the manufacturer, who adds the cost of the energy that is used to the cost of the power supply product.